Skeptics weigh in as doctor details his belief in an afterlife, or at least a sequel

As near-death experiences go, this one was a doozy. Loaded with puffy pink clouds, silver-bodied angels and surreal explosions of color, it lasted nearly seven days, the longest afterlife episode since Lazarus (who, regrettably, didn't write a bestselling book about his time in the tomb).

The strange incident also upends scientific arguments that near-death visions are vivid tricks of the brain. Or so says Eben Alexander, a Harvard-trained neurosurgeon with a soothing Southern drawl and a penchant for bow ties.

In his chart-topping book, "Proof of Heaven," the 59-year-old physician recounts his brush with death and makes a case that his experience defies medical explanation.

Skeptics have assailed the story.

Alexander isn't the first near-death voyager to stir controversy. For years, people who've been resuscitated after cardiac arrest have reported floating out of their bodies to otherworldly realms, often encountering deceased loved ones and divine beings.

Scientists concede such visions are startling, but that doesn't mean they're real. For openers, people don't have to be "dead" to have them. Miners trapped underground, prisoners of war and hostages have described similar trips to heaven, researchers note.

Another problem: Near-death tales often vary according to a person's culture and beliefs. For example, American afterlife visitors typically say God sent them back because "it's not your time yet." In contrast, India's near-death survivors are told there was a "clerical error."

Also, in centuries past, postmortem voyagers frequently went to purgatory or hell, whereas today's sojourners ascend to a decidedly nonjudgmental heaven, according to author Carol Zaleski's "Otherworld Journeys," a comparison of modern and ancient near-death accounts.

In short, although such visions are gripping and vivid, they are "happening in the landscape of the mind," says Ronald K. Siegel, a hallucination expert who taught bio-behavioral sciences at UCLA.

Alexander insists such rationales don't apply in his case. He says his near-death vision happened while his neocortex was completely shut down by a deadly case of meningoencephalitis, a real-life version of the fictional bug that wiped out millions in the movie "Contagion."

That means it was impossible for his brain to have created the things he saw and heard, Alexander says. In a coma for one week and given a 3% chance of survival as bacteria gnawed on his cortex, Alexander found himself in a psychedelic realm dotted with pink clouds, where he rode a giant butterfly, listened to the singing of silver beings and absorbed "explosions of light, color, love and beauty," he says. Trying to describe heaven, he adds, is like being a chimpanzee who turns human for a day, then attempts to relay the experience to other apes. Words fail.

Mark Tuszynski, a practicing neurologist and professor of neurosciences at UC San Diego, doesn't buy Alexander's claim that his cortex was totally shut down and his brain cells too damaged to produce the detailed visions described in "Proof of Heaven." The fact that Alexander recovered fully, with no lasting neurological problems, indicates his brain still had enough power during the coma to cause "a dreamlike state," Tuszynski says. "If function had been lost, recovery would not have occurred."

Siegel, the hallucination expert, agrees. If Alexander's cortex had truly flat-lined, he wouldn't even be able to remember any near-death visions, he says. "Memory is a cognitive experience," Siegel explains. To record a sight, sound or other sensory input, the brain has to be working.

Alexander says he used to agree with that view but now believes "some form of memory exists independently of the brain," in a spiritual realm.